The present invention relates to a shear restraint on a main rotor. More specifically, but without limitation, the present invention relates to a helicopter flex beam main rotor shear restraint.
A main rotor on a helicopter is the main system of rotating airfoils of a helicopter. The main rotor is considered to be an important part of the helicopter. It provides the lift that allows the helicopter to fly, as well as the control that allows the helicopter to move laterally, make turns and change altitude. The main rotor of a helicopter must be able to adjust the angle of the rotor blades in order to perform these various maneuvers.
The main rotor typically has a yoke, which can be defined, but without limitation, as a flexure that retains the helicopter blades of the main rotor. The rotating controls adjust the angle of the rotor blades with each revolution of the rotor. Bearings within the main rotor system allow for movement of the main rotor components while reacting the loads. Certain bearings, such as the shear restraint bearing, accommodate the blade feathering (blade feathering can be defined, but without limitation, as the action of changing a blade angle of a controllable pitch propeller) and flapping motions, and react the blade loads.
In a typical helicopter, main rotor self-lubricated shear restraint bearings become loose due to bearing wear. This can create a play in the bearings and reduce the effectiveness of the lead-lag damper. A lead-lag damper is needed in flex beam rotors in order to provide the necessary lead-lag damping to the rotor system. A system is needed to prevent these bearings from becoming loose due to bearing wear.
Furthermore, standard yokes typically require a hole in the yoke. Having a hole makes the design of the yoke more complicated, as well as potentially creating weak spots in the yoke. A system is needed that eliminates the need for a hole in the yoke.
Thus, there is a need in the art to provide a main rotor shear restraint that incorporates the listed benefits without the limitations inherent in present methods. For the foregoing reasons, there is a need for a main rotor shear restraint.